US4423932A - Eye fundus observing and photographing optical system - Google Patents

Eye fundus observing and photographing optical system Download PDF

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Publication number
US4423932A
US4423932A US06/214,043 US21404380A US4423932A US 4423932 A US4423932 A US 4423932A US 21404380 A US21404380 A US 21404380A US 4423932 A US4423932 A US 4423932A
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sub
eye
lens
apertured mirror
lens component
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Fumio Takahashi
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Nikon Corp
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Nippon Kogaku KK
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Assigned to NIPPON KOGAKU K.K., A CORP. OF JAPAN reassignment NIPPON KOGAKU K.K., A CORP. OF JAPAN ASSIGNMENT OF ASSIGNORS INTEREST. Assignors: TAKAHASHI FUMIO
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Assigned to NIKON CORPORATION, 2-3, MARUNOUCHI 3-CHOME, CHIYODA-KU, TOKYO, JAPAN reassignment NIKON CORPORATION, 2-3, MARUNOUCHI 3-CHOME, CHIYODA-KU, TOKYO, JAPAN CHANGE OF NAME (SEE DOCUMENT FOR DETAILS). EFFECTIVE APR. 1, 1988 Assignors: NIPPON KOGAKU, K.K.
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    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
    • A61B3/00—Apparatus for testing the eyes; Instruments for examining the eyes
    • A61B3/10—Objective types, i.e. instruments for examining the eyes independent of the patients' perceptions or reactions
    • A61B3/14—Arrangements specially adapted for eye photography

Definitions

  • This invention relates to a device for observing and photographing the fundus of an eye, and particularly to the optical system thereof.
  • an objective lens In an eye fundus observing and photographing optical system of the type in which an objective lens is used in common for an illuminating optical system and an observing/photographing optical system, if the reflected light by the surface of the objective lens of the illuminating optical system mixes with the observation/photographing light beam, the quality of the image of the eye fundus will be greatly deteriorated. For this reason, various contrivances have heretofore been made, but the curvatures of the lens surfaces and the number of lenses have been limited for the elimination of the reflected light and it has been very difficult to design an objective lens which enables observation and photographing over a wide angle of view.
  • FIG. 1 of the accompanying drawings shows an example of the eye fundus photographing optical system using a meniscus type objective lens heretofore widely used.
  • E designates an eye to be examined
  • C a cornea
  • L 0 a meniscus type objective lens
  • M an apertured mirror
  • L 1 a relay lens of the photographing system
  • F a film surface.
  • An illuminating lamp l illuminates a ring slit S through a condenser lens L 3 .
  • This ring slit S is once imaged near the position of the apertured mirror M disposed obliquely with respect to the optical axis by a relay lens L 2 of the illuminating system, and is further imaged on the corner C of the eye E by the objective lens L 0 through the apertured mirror M, thus illuminating the fundus of the eye.
  • the light beam leaving the fundus of the eye E passes through the center of the pupil of the eye and once forms an inverted eye fundus intermediate image I by the objective lens L 0 , and then passes through the opening portion of the apertured mirror M and forms an erect eye fundus image on the film surface F by the relay lens L 1 of the photographing system.
  • the illuminating light beam is separated from the photographing light beam passing through the center of the pupil of the eye E by a so-called ring illumination using the ring slit S.
  • the center of curvature of the second surface r 2 thereof is the position at which the apertured mirror intersects the optical axis and therefore, the light beam emitted from the central position returns along the same light path when reflected by the surface r 2 . That is, the position at which the apertured mirror M intersects the optical axis is in equal magnification and real conjugate relation with respect to the reflecting surface which is the second surface r 2 of the objective lens L 0 and therefore, if the illuminating light beam and the photographing light beam are separate from each other like the well-known ring illumination, the reflected light of the illuminating system by the second surface r 2 will never mix with the photographing light beam.
  • the curvature of the first surface r 1 is determined so that the reflected light of the illuminating system by this surface gathers near the vertex of the second surface r 2 , and a black point P of sufficient size to intercept the reflected light passing through the opening portion of the apertured mirror M may be disposed near the vertex of the second surface r 2 , thereby eliminating the reflected light in this surface.
  • a black point P of sufficient size to intercept the reflected light passing through the opening portion of the apertured mirror M may be disposed near the vertex of the second surface r 2 , thereby eliminating the reflected light in this surface.
  • the eye fundus observing and photographing optical system has an objective lens including a main positive lens component and at least one positive lens component provided at that side of said main positive lens component which is adjacent to an eye to be examined, and an illuminating optical system including an apertured mirror disposed obliquely with respect to the optical axis of said objective lens to supply an illuminating light to the fundus of said eye through said objective lens.
  • the reflected image position of the opening portion of said apertured mirror by the lens surface of said at least one positive lens component which is adjacent to said eye is made substantially coincident with a first position P 1 whereat the reflected image of the opening portion of said apertured mirror by the lens surface of said main positive lens component which is adjacent to said eye is formed, and the reflected image position of the opening portion of said apertured mirror by the lens surface of said at least one positive lens component which is adjacent to said apertured mirror is made substantially coincident with a second position P 2 which is more adjacent to said eye than said first position.
  • FIG. 1 shows an example of the eye fundus photographing optical system according to the prior art.
  • FIGS. 2 and 3 are lens construction views of a first and a second embodiment of the objective lens according to the present invention.
  • FIG. 4 shows an objective lens having a cemented surface for the correction of chromatic aberration in the first embodiment.
  • FIG. 5 shows an objective lens having a cemented surface for the correction of chromatic aberration in the second embodiment.
  • FIG. 6 shows an example in which a positive lens is further added to the objective lens of FIG. 5.
  • FIG. 7 shows an example of the eye fundus observing and photographing optical system using the objective lens of FIG. 4.
  • FIGS. 2 and 3 are lens construction views of a first and a second embodiment of the objective lens according to the present invention, and for simplicity of illustration, the cemented surfaces of the lens are not shown therein and of the optical system of the eye fundus camera, only the eye E to be examined and an apertured mirror M are shown therein.
  • the first embodiment of FIG. 2 uses a biconvex type lens as a main positive lens and combines therewith a positive meniscus lens having its concave surface facing the examined eye side as a lens having a positive refractive power.
  • the successive lens surfaces are defined as r 1 , r 2 , r 3 and r 4 in succession from the examined eye side, the light reflected by the odd-numbered lens surfaces, namely, the surfaces of the successive lenses which are adjacent to the examined eye side, exits toward the apertured mirror side and forms a reflected image of the opening portion of the apertured mirror, and the curvatures of these surfaces are determined so that the position of the reflected image is coincident with or near a first position which is a point P 1 adjacent to the apertured mirror side, and likewise, the curvatures of the even-numbered lens surfaces, namely, the surfaces of the successive lenses which are adjacent to the apertured mirror side, are determined so that the reflected image of the illuminating system formed by such surfaces is coincident with or near a
  • the second embodiment shown in FIG. 3 uses, as a main positive lens component, a conventional meniscus type lens as shown in FIG. 1 and combines a positive meniscus lens having its concave surface facing the examined eye side and a biconvex lens as two lenses having a positive refractive power on the examined eye side. If the successive lens surfaces are defined as r 1 , r 2 , . . .
  • the center of curvature of the last surface r 6 is positioned at a point whereat the apertured mirror intersects the optical axis and therefore, as in the case of the conventional meniscus type lens, of the illuminating light, the light reflected by this surface r 6 does not pass through the opening portion of the apertured mirror to mix with the phototaking light path.
  • the curvatures of the successive surfaces are determined so that, as in the first embodiment, the position of the reflected image by the odd-numbered surfaces of r 1 to r 5 , namely, the lens surfaces which are adjacent to the examined eye side, is coincident with or near the first position which is the point P 1 adjacent to the apertured mirror side, of the two points P 1 and P 2 , while the reflected image by the even-numbered surfaces is coincident with or near the second position which is the point P 2 adjacent to the examined eye side.
  • the size of a black point or a black point image to be set at the two locations on which the reflected image concentrates is determined by the size of the reflected image, namely, the magnification of the reflected image and therefore, it is necessary to make this magnification as small as possible. Also, from various points of view, it is desirable that the two points P 1 and P 2 be set under the following conditions.
  • positions P 1 and P 2 whereat the reflected image is formed be in the following ranges.
  • the curvature radius of the surface of the lens surfaces which is adjacent to the examined eye side becomes smaller and correspondingly, the curvature radius of the surface r 2 also becomes smaller in connection with condition (II), and the refractive powers in these surfaces become excessively great and the operating distance becomes shorter. Accordingly, if the lower limit of said range is exceeded, the curvature radius of the surface r 1 also becomes smaller in both the type of FIGS.
  • the upper limit of said range is exceeded, a large black point will become necessary and the shadow of the black point will be created in the observation view field and the device will become impractical.
  • the first position P 1 lies on the apertured mirror side, it becomes near the position of the eye fundus image, particularly, the eye fundus image position of emmetropia or hypermetropia and the black point becomes liable to be conspicuous in the eye fundus image and also, the refractive power of each lens surface becomes smaller and cannot correspond to a wide angle of view and therefore, from these points of view, said range is desirable.
  • the curvature radii of the surfaces of the lenses which are adjacent to the apertured mirror side (in the first type of FIG. 2, the surface r 2 and particularly the surface r 4 , and in the second type of FIG. 3, the surfaces r 2 and r 4 ) become greater, and the image of the opening portion of the apertured mirror by the light rays reflected by these lens surfaces becomes larger, and the black point required to intercept the reflected light also becomes larger.
  • the reflected image magnification in these lens surfaces exceeds 0.8-0.9, and a large black point comparable to a ring slit image formed at the position of the apertured mirror is required and the shadow of the large black point is created in the center of the view field.
  • the refractive power of each lens surface becomes smaller and it becomes difficult to maintain a wide angle of view.
  • the surface r 4 and particularly the surface r 2 become smaller and the refractive powers in these surfaces become excessively great and the operating distance becomes shorter. If said range is exceeded, in both the types of FIGS. 2 and 3, the curvature radius of the surface r 1 will become smaller and this, coupled with the fact that the operating distance is extremely short, comes to cover the eyeball and becomes actually unusable.
  • a conjugate black point or a black point image generally lies near the eye fundus image position of an intense myopia and therefore, during the photographing of emmetropia or weak myopia, the black point image is not conspicuous due to the defocus.
  • the black point or the black point image lies near the eye fundus image position of emmetropia and further, of hypermetropia, and therefore, the frequency with which a clear black point is photographed becomes higher, thus hampering the observation of the eye fundus image.
  • the curvature of the cemented surface may be chosen so that even the position of the reflected image of the opening portion of the apertured mirror by the cemented surface is coincident with said point P 1 or P 2 , and the curvature of the cemented surface is determined with the chromatic aberration or the like taken into account.
  • the biconvex main positive lens is provided with two cemented surfaces, namely, a cemented surface r 30 having its convex surface facing the mirror side and a cemented surface r 31 having its concave surface facing the mirror side, so that the reflected image position by the former r 30 is coincident with the point P 2 and the reflected image position by the latter r 31 is coincident with the point P 1 .
  • the second type shown as the second embodiment in FIG. 3 as shown in FIG.
  • a meniscus-shaped main positive lens component is provided with a cemented surface r 51 having its convex surface facing the mirror side, so that the reflected image position by this cemented surface is coincident with the point P 1 .
  • FIGS. 4 and 5 of the reflected light reflected by each surface, only the light rays reflected by the cemented surfaces are indicated by dotted lines. The conditions of the reflected light on the surface in contact with the air are as shown in FIGS. 2 and 3.
  • cemented surfaces for the correction of the chromatic aberration be determined with the reflected image position being further taken into consideration as follows.
  • the position P 1 should more desirably be up to about -1/4d 2 , namely, -1/4d 2 ⁇ P 1 ⁇ d 2 .
  • the position P 1 should more desirably be up to -(1/10)d 2 , namely, as narrow as -1/3d 2 ⁇ P 1 ⁇ -(1/10)d 2 .
  • the points P 1 and P 2 of the reflected image position and the position in real conjugate relation with respect to a relay lens L 2 are respectively obtained in the illuminating system and a black point of a sufficient size to intercept the reflected light from each lens surface is disposed at each of conjugate positions P' 1 and P' 2 , thereby preventing the reflected light from mixing with the phototaking light beam.
  • the reflected image of each surface is all in real conjugate relation, the same effect can of course be obtained even if a real black point is placed at the conjugate position of the objective lens.
  • d 0 represents the distance between the examined eye and the vertex of the first surface r 1 of the objective lens, namely, the operating distance, d 6 ' in the first embodiment and d 7 ' in the second embodiment respectively represent the distance between the last surface of the objective lens and the center of the opening portion of the apertured mirror.
  • FIG. 6 shows an example in which a positive lens is added to the objective lens of the second type shown in FIG. 5 to provide a wider angle of view.
  • the reflected image is concentrated while being divided into two locations, i.e. the points P 1 and P 2 , and a black point or a black point image is provided or formed at each of these two locations, whereby harmful reflected light in the lens surface can be sufficiently intercepted while a very wide angle of view is maintained.
  • a wide angle of view can be provided by adding a positive lens while keeping said relation.
  • a wider angle of view can be provided by increasing the number of positive lenses, but generally the operating distance becomes shorter and therefore, the number of lenses is naturally limited.
  • the reflected light in each lens surface can be sufficiently intercepted and an excellent observed image and photographed image can be obtained while keeping a very wide angle of view.

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  • Life Sciences & Earth Sciences (AREA)
  • Health & Medical Sciences (AREA)
  • Medical Informatics (AREA)
  • Biophysics (AREA)
  • Ophthalmology & Optometry (AREA)
  • Engineering & Computer Science (AREA)
  • Biomedical Technology (AREA)
  • Heart & Thoracic Surgery (AREA)
  • Physics & Mathematics (AREA)
  • Molecular Biology (AREA)
  • Surgery (AREA)
  • Animal Behavior & Ethology (AREA)
  • General Health & Medical Sciences (AREA)
  • Public Health (AREA)
  • Veterinary Medicine (AREA)
  • Eye Examination Apparatus (AREA)
US06/214,043 1979-12-25 1980-12-08 Eye fundus observing and photographing optical system Expired - Lifetime US4423932A (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
JP54-167645 1979-12-25
JP16764579A JPS5691729A (en) 1979-12-25 1979-12-25 Optical system for examinating and photographing eyeground

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Cited By (11)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE3519442A1 (de) * 1984-05-30 1985-12-05 Tokyo Kogaku Kikai K.K., Tokio/Tokyo Optisches system fuer eine netzhautkamera
DE4141087A1 (de) * 1990-12-11 1992-06-17 Topcon Corp Funduskamera
US5291885A (en) * 1990-11-27 1994-03-08 Kowa Company Ltd. Apparatus for measuring blood flow
US5943116A (en) * 1997-04-01 1999-08-24 Johns Hopkins University System for imaging an ocular fundus semi-automatically at high resolution and wide field
US20050110949A1 (en) * 2003-10-28 2005-05-26 Welch Allyn, Inc. Digital documenting ophthalmoscope
US6939006B2 (en) 1998-11-24 2005-09-06 Welch Allyn, Inc. Eye viewing device for large field viewing
US7311401B2 (en) 1998-11-24 2007-12-25 Welch Allyn, Inc. Eye viewing device comprising eyepiece and video capture optics
US20080309876A1 (en) * 2007-06-15 2008-12-18 Massie Norbert A Method And Apparatus For Imaging An Eye Of A Small Animal
CN111035361A (zh) * 2019-12-28 2020-04-21 重庆贝奥新视野医疗设备有限公司 一种眼底相机成像和照明系统
CN113495345A (zh) * 2020-04-01 2021-10-12 因德斯马特有限公司 眼用成像系统
US20230270328A1 (en) * 2016-08-31 2023-08-31 Nikon Corporation Wide-angle pupil relay for cellphone-based fundus camera

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4162827A (en) 1976-06-09 1979-07-31 Canon Kabushiki Kaisha Wide angle objective for ophthalmoscopic instrument
US4176920A (en) 1976-05-19 1979-12-04 Canon Kabushiki Kaisha Ophthalmoscopic system with a wide angle objective lens
US4322137A (en) 1978-12-29 1982-03-30 Nippon Kogaku K.K. Fundus observation and photographing optical system

Family Cites Families (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE2532558C2 (de) * 1975-07-21 1983-03-03 Siemens AG, 1000 Berlin und 8000 München Schaltungsanordnung für ein Remanenzrelais
JPS54148091U (enrdf_load_stackoverflow) * 1978-04-06 1979-10-15

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4176920A (en) 1976-05-19 1979-12-04 Canon Kabushiki Kaisha Ophthalmoscopic system with a wide angle objective lens
US4162827A (en) 1976-06-09 1979-07-31 Canon Kabushiki Kaisha Wide angle objective for ophthalmoscopic instrument
US4322137A (en) 1978-12-29 1982-03-30 Nippon Kogaku K.K. Fundus observation and photographing optical system

Cited By (16)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE3519442A1 (de) * 1984-05-30 1985-12-05 Tokyo Kogaku Kikai K.K., Tokio/Tokyo Optisches system fuer eine netzhautkamera
US5291885A (en) * 1990-11-27 1994-03-08 Kowa Company Ltd. Apparatus for measuring blood flow
DE4141087A1 (de) * 1990-12-11 1992-06-17 Topcon Corp Funduskamera
US5943116A (en) * 1997-04-01 1999-08-24 Johns Hopkins University System for imaging an ocular fundus semi-automatically at high resolution and wide field
US7784940B2 (en) 1998-11-24 2010-08-31 Welch Allyn, Inc. Eye viewing device comprising video capture optics
US6939006B2 (en) 1998-11-24 2005-09-06 Welch Allyn, Inc. Eye viewing device for large field viewing
US7311401B2 (en) 1998-11-24 2007-12-25 Welch Allyn, Inc. Eye viewing device comprising eyepiece and video capture optics
US20080030683A1 (en) * 1998-11-24 2008-02-07 Ervin Goldfain Eye viewing device comprising video capture optics
US7364297B2 (en) 2003-10-28 2008-04-29 Welch Allyn, Inc. Digital documenting ophthalmoscope
US20050110949A1 (en) * 2003-10-28 2005-05-26 Welch Allyn, Inc. Digital documenting ophthalmoscope
US20080309876A1 (en) * 2007-06-15 2008-12-18 Massie Norbert A Method And Apparatus For Imaging An Eye Of A Small Animal
US7993000B2 (en) 2007-06-15 2011-08-09 Phoenix Research Laboratories Method and apparatus for imaging an eye of a small animal
US20230270328A1 (en) * 2016-08-31 2023-08-31 Nikon Corporation Wide-angle pupil relay for cellphone-based fundus camera
US12156698B2 (en) * 2016-08-31 2024-12-03 Nikon Corporation Wide-angle pupil relay for cellphone-based fundus camera
CN111035361A (zh) * 2019-12-28 2020-04-21 重庆贝奥新视野医疗设备有限公司 一种眼底相机成像和照明系统
CN113495345A (zh) * 2020-04-01 2021-10-12 因德斯马特有限公司 眼用成像系统

Also Published As

Publication number Publication date
JPS5691729A (en) 1981-07-24
JPH0120896B2 (enrdf_load_stackoverflow) 1989-04-19

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